This project deals with the genetic and biochemical analysis of bacterial mutants unable to assemble ribosome subunits at low temperature. Among such mutants we have found several groups in which the genetic lesions map outside the strspc region of the chromosome, and which map away from each other. Such mutants may be altered in factors that participate in the assembly process, but which are not structural components of the ribosome. We wish to study further the possible role of phosphorylation of ribosomal proteins in the fungus Mucor as it might bear on the ribosome assembly process, and in relation to the morphogenetic cycle of the organism.